Tube clamp



P 30,,1946- R. R. HARRISON 2,399,183

TUBE CLAMP Filed Oct. 10, 1941 INVENTOR ROBERT R. HARRISON Patented Apr. 30, 1946 TUBEOLAMP Robert R. Harrison, North Hollywood, Calif., asslgnor, by mesne assignments, to Bendix Aviation Corporation, South Bend, 11111., a corporation of Delaware Application October 10, 1941, Serial No. 414,417

2 Claims.

. vided with means to electrically ground any tube or conduit held in the clamp.

Some of the structures herein disclosed are claimed in my divisional application, Serial No. 620,208, filed October 4, 1945.

One object of the invention is to provide a tube clamp having an electrical groundingstrip provided with a curved portion to accommodate vibration well within the elastic limit of the strip.

Another object of the invention is to provide atube clamp with an electrical grounding strip which is rigidly aligned with the metal loop forming the main element of the clamp.

Other objects and advantages of the invention will be apparent in the following description and claims taken in connection with the accompanying drawing in which:

Figure 1 is an isometric view of a tube clamp embodying th invention, with a segment or a tube clamped therein;

Figure 2 is an elevation of a segment of the tube clamp of Figure 1 showing a portion of the cushion of the clamp and the electrical grounding strip overlying the cushion:

Figure 3 is an elevation of a portion 01 the clamp 01 Figure 1 in its final Iorm, showing expansion bend in the electrical conducting strip;

Figure 4 is an isometric view of a modification of the invention showing one end of the electrical grounding strip bent over the cushion element; and

Figure 5 is an isometric view of a portion of the strip of the loop of Figure 4, showing the grounding strip welded to the metal loop, and showing the cushion in dotted outline.

For the present purposes, it will be stated that the clamp is used to hold conduits to any structural member of the vehicle in which they are mounted. They are particularly adapted for use in airplanes, and for this purpose a cushion element must be provided to prevent injury to the clamped tube due to the intense vibrations found in airplanes. However, it has been found that static charges accumulate on conduits held in an insulating material such as is commonly employed. as the cushion element, and electrical grounding strips are employed to remove the static charges, which present a fire hazard, as well as an. interference to radio operation, when they discharge across an air gap.

' The clampof Figure 1 comprises a metal strip it of aluminum, or where great strength is required, or stainless steel. ,The metal strip I is bent to a rounded shape so as to form a loop to encircle any tube or conduit l2 which may be held therein. One end I or the strip I II is bent at right angles to the .body 01' the strip,

so as to be parallel with the other end, permitting a screw ii to be passed through both ends to secure the clamp as a whole to any member. The clamp is provided with a cushion ll which is preferably. 01' a resilient material such as the commonly available synthetic rubber-like materials which are resistant to oil and gasoline. Since such cushions are usually insulators, a grounding strip 2! is secured to the loop metal I0, and overlies the cushion It so as to electrically ground any conduit to the metal oi the clamp loop "I. p

The loop strips iii are first formed in a flat position, and the cushion material It is vulcango ized or bonded to the strip l0 by methods well known to the art. The grounding strip is then secured to the strip I 0 by a hollow rivet 22 passing through hole 24 in one end or strip ill. The construction thus far described is common 25 in the tube clamp art, but under severe operating conditions where vibration is intense, it has been found that the grounding strip ill! tends to swivel on its rivet 22 and work of! of the cushion i8 under which condition it no longer grounds the conduit 12. Further, it has been found that the vibrationcausee minute reversals o1 stresss in grounding strip 20 in a direction to cause alternate tension and compression. Such reversals or stress set up a fatigue condition which sometimes causes the conducting tag 20 to crack near its rivet 22.

Both of these undesirable conditions are eliminated in the present invention by vulcanizing or bonding the strip 20 to the cushion l8, and as has already been explained the cushion i8 is bonded to the strip Ill. The strip 20 is bonded to the cushion i8 while the entire clamp is in a ilat position as shown in Figure 2. When the clamp is bent to its final form, the strip 20 will be on the inside of the loop and consequently will buckle in any free region to accommodate the lesser radius during the bending. This buckle or crimp in strip 20 is shown in Figure 3 at 28. I

The construction described provides an expansion bend 2B in the final clamp which will accommodate stresses in the strip 20 which are well within the elastic limit of the material in the strip. Further, the bonding of the strip 20 55 to cushion I8 insures that it will not swivel about its rivet and therefore work out of contact with any conduit l2 held in the clamp.

The clamp of Figure 4 comprises a loop of metal 40 formed in a shape similar to strip I! of Figure 1. A cushion fl overlies the curved portions of strip ill, and a grounding tag 44 electrically connects any conduit with the strip ll. As seen in Figure 5, the strip 44 is welded to strip 4. by a.

spot weld 48 before the cushion element 02 is applied to the assembly. After bonding the cushion 42 to strips l0 and 44, the outer end of the strip 44 is bent upwardly and then over to overlie a portion of cushion 42, as shown in Figure 4.

The construction of Figures 4 and 5 has the same advantages as the construction of Figures 1, 2 and 3. Since the grounding tag 44 is welded to the loop metal Ill rather than riveted, it is impossible for any swiveling action to take place such as will allow movement of the tag 44 off of cushion 42. The bend in grounding strip 44 at the region ll gives a suflicient are or curvature in the tag 44 so as to accommodate any reversals of stress well within the elastic limit of the material. Thus both embodiments of the invention insure freedom from fatigue cracks, and insure that the grounding strip will always overlie the cushion.

Although this invention has been described with reference to particular embodiments thereof, it is not limited to these embodiments or otherwise except by the terms of the following claims.

I claim:

1. A tube clamp comprising a loop of metal having holes in the ends, a cushion of rubber-like material bonded to the inner surface of the loop.

and a grounding strip riveted to the hole in one end of said loop and bonded to the inner surface of said cushion.

2. A tube clamp comprising a loop of metal, a cushion of rubber-like material bonded to the inner surface thereof, and a grounding strip secured to the metal loop and bonded to the inner surface of said cushion and having a pronounced bend therein to accommodate fatigue stresses.

ROBERT R. HARRISON. 

